Insertion instrument for expandable spinal implants

ABSTRACT

An insertion instrument for expandable spinal implants includes an elongate member, a shuttle, and a worm gear. The elongate member includes a handle portion of a proximal end and an end effector on a distal end, wherein the end effector is configured to be releasably engaged to an expandable spinal implant. The shuttle is slidably disposed within a cavity defined within the end effector and includes a wedged shaped distal end configured to engage an expandable spinal implant. The worm gear is rotatably disposed within the cavity defined in the end effector and is in mechanical communication with the shuttle, such that rotation of the worm gear effectuates movement of the shuttle. Distal movement of the shuttle effectuates articulation of an expandable spinal implant. A method of performing surgery is also disclosed.

BACKGROUND

Technical Field

The present disclosure relates generally to devices and methods fortreating spinal conditions, and in particular, to insertion instrumentsconfigured for positioning expandable spinal implants within anintervertebral space.

Background of the Disclosure

After a partial or complete discectomy, the normally occupied spacebetween adjacent vertebral bodies may collapse and/or become misaligneddue to the absence of all or a part of the intervertebral disc. In thesesituations, a physician may insert one or more prosthetic spacersbetween the affected vertebrae to maintain normal disc spacing and/orthe normal amount of lordosis in the affected region.

Typically, a prosthetic implant is inserted between the adjacentvertebrae and may include pathways that permit bone growth between theadjacent vertebrae until they are fused together. However, there existsa possibility that conventional prosthetic implants may be dislodged ormoved from their desired implantation location due to movement by thepatient before sufficient bone growth has occurred.

Additionally, achieving the desired lordosis can be difficult given thelimitations of typical prosthetic implants once they are implanted.

To solve these issues, implants capable of providing a desired amount oflordosis, allowing for bone growth between adjacent vertebrae,maintaining the space between adjacent vertebrae during bone ingrowth,and resisting dislocation from its implantation site have beendeveloped. However, effectively implanting such devices can bedifficult. Therefore, a need exists for insertion instruments capable ofinserting an expandable spinal implant between adjacent vertebrae,manipulating the spinal implant to provide the desired amount oflordosis, and locking the implant in the position providing the desiredamount of lordosis.

SUMMARY

In accordance with the present disclosure, an insertion instrument forexpandable spinal implants including an elongate member, a shuttle, anda worm gear is provided. The elongate member includes a handle portionon a proximal end thereof and an end effector on a distal end thereof.The end effector is configured to be releasably engaged to an expandablespinal implant. The shuttle is slidably disposed within a cavity definedin the end effector. The shuttle includes a wedge shaped distal endconfigured to engage an expandable spinal implant. The worm gear isrotatably disposed within the cavity defined in the end effector and isin mechanical communication with the shuttle such that rotation of theworm gear effectuates movement of the shuttle. Distal movement of theshuttle effectuates articulation of an expandable spinal implant.

In aspects, the insertion instrument may include a first tool capable ofcoupling the end effector to an expandable spinal implant.

In other aspects, the insertion instrument may include a second toolcapable of engaging the worm gear and effectuating rotation thereof.

In certain aspects, the elongate member may further include a pluralityof throughholes defined therethrough.

In some aspects, the plurality of throughholes may include a firstthroughhole configured to receive the second tool therethrough.

In certain aspects, the plurality of throughholes may include a secondand a third throughhole configured to receive the first tooltherethrough to enable the end effector to be releasably secured to anexpandable spinal implant.

In other aspects, the plurality of throughholes may include a fourththroughhole configured to receive the first tool therethrough to lock aposition of a lower body in relation to a position of an upper body ofan expandable spinal implant.

In aspects, the insertion instrument may include a plurality of screws,wherein each of the second and third throughholes is configured toreceive a respective screw of the plurality of screws therein, theplurality of screws being configured to releasably couple the endeffector to an expandable spinal implant.

In certain aspects, the cavity defined in the end effector may include apair of opposed rails disposed on side surfaces thereof. The pair ofopposed rails may be configured to slidably engage a corresponding pairof opposed slots defined within side surfaces of the shuttle.

An expandable spinal implant is also provided in accordance with thepresent disclosure and includes an upper body, a lower body, a ratchetmechanism, a biasing element, and a plurality of bone screws. The upperand lower bodies are affixed at a first end and are capable of movementrelative to each other. The upper and lower bodies are dimensioned to beinstalled between two vertebral bodies and the outer surfaces of eachare adapted to engage a corresponding end plate of the two vertebralbodies. Screw holes are defined through the outer surface and anadjacent side surface of the upper body and through the outer surfaceand an adjacent side surface of the lower body. The screw holes areoriented toward a respective adjacent one of the two vertebral bodies atan oblique angle. The ratchet mechanism is slidably disposed on one ofthe upper and lower bodies and is capable of engaging the opposite oneof the upper and lower bodies. The biasing element is capable of biasingthe ratchet mechanism in a direction such that the upper and lowerbodies are capable of articulating relative to each other in a firstdirection, but not in a second direction. Each bone screw of theplurality of bone screws is insertable through a corresponding screwhole of the upper body and the lower body and are capable of beingattached to bone.

A method of performing surgery provided in accordance with the presentdisclosure includes releasably securing an insertion instrument to anexpandable spinal implant, the insertion instrument including anelongate member, a shuttle, and a worm gear. The elongate memberincludes a handle portion on a proximal end thereof and an end effectoron a distal end thereof. The end effector is configured to be releasablyengaged to an expandable spinal implant. The shuttle is slidablydisposed within a cavity in the end effector and includes a wedge shapeddistal end configured to engage an expandable spinal implant. The wormgear is rotatable disposed within the cavity defined in the endeffector. The worm gear is in mechanical communication with the shuttlesuch that rotation of the worm gear effectuates movement of the shuttle.Distal movement of the shuttle effectuates articulation of an expandablespinal implant.

The method also includes positioning an upper body and a lower body ofthe expandable spinal implant in a first, approximated position relativeto each other, inserting the expandable spinal implant into a preparedintervertebral space, and rotating the worm gear to effectuate distalmovement of the shuttle such that the shuttle causes the lower body ofthe expandable spinal implant to articulate relative to the upper body,thereby effectuating a desired lordosis of a spine of a patient.

In aspects, the method may include inserting a plurality of bone screwswithin a plurality of screw holes defined in each of the upper and lowerbodies of the expandable spinal implant and into respective vertebralbodies.

In some aspects, the method may include locking the upper and lowerbodies of the expandable spinal implant relative to each other.

In other aspects, the method may include removing the insertioninstrument from the expandable spinal implant.

In certain aspects, releasably securing the insertion instrument to theexpandable spinal implant may include engaging a first tool to aplurality of screws disposed within the end effector of the insertioninstrument. The plurality of screws may be configured to threadablyengage a corresponding plurality of threaded holes defined in the upperbody of the expandable spinal implant.

In some aspects, rotating the worm gear may include engaging a secondtool to the worm gear such that rotation of the second tool effectuatesrotation of the worm gear.

In aspects, rotating the worm gear may include advancing the second toolthrough a first throughhole defined through the elongate member of theinsertion instrument such that the second tool engages the worm gear.

In other aspects, releasably securing the insertion instrument to theexpandable spinal implant includes advancing the first tool through asecond and a third throughhole defined through the elongate member ofthe insertion instrument such that the first tool engages each screw ofthe plurality of screws.

In certain aspects, locking the upper and lower bodies of the expandablespinal implant includes engaging a first tool to a ratchet screwrotatably disposed on the upper body. The ratchet screw may threadablyengage a ratchet mechanism slidably disposed on the upper body, whereinrotation of the ratchet screw causes a plurality of teeth disposed onthe ratchet mechanism to engage a corresponding plurality of teethdisposed on the lower body of the expandable spinal implant therebylocking the upper body relative to the lower body.

In some aspects, locking the upper and lower bodies of the expandablespinal implant includes advancing the first tool within a fourththroughhole defined through the elongate member of the insertioninstrument.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a rear, perspective view, of an expandable spinal implantprovided in accordance with the present disclosure;

FIG. 2 is an exploded view, with parts separated, of the expandablespinal implant of FIG. 1;

FIG. 3 is a side view of the expandable spinal implant of FIG. 1;

FIG. 4A is a top view of a bone screw usable with the expandable spinalimplant of FIG. 1;

FIG. 4B is a side view of the bone screw of FIG. 4A;

FIG. 4C is a side, cross-sectional view, of the bone screw shown in FIG.4B;

FIG. 5 is a rear, perspective view, of an insertion instrument and theexpandable spinal implant of FIG. 1 provided in accordance with thepresent disclosure;

FIG. 6 is a rear view of the insertion instrument of FIG. 5;

FIG. 7A is an enlarged view of the area of detail indicated in FIG. 5;

FIG. 7B is an front, perspective view, of the enlarged view of FIG. 7A;

FIG. 8A is a rear, perspective view, of the insertion instrument of FIG.5, shown with a first tool;

FIG. 8B is a rear, perspective view, of the insertion instrument of FIG.5, shown with the first tool of FIG. 8A advanced within a secondthroughhole defined therein;

FIG. 9A is a rear, perspective view, of the insertion instrument of FIG.5, shown with a second tool;

FIG. 9B is a rear, perspective view, of the insertion instrument of FIG.5, shown with the second tool of FIG. 9A advanced within a firstthroughhole defined therein;

FIG. 10A is a side view of the insertion instrument of FIG. 5 coupled tothe expandable spinal implant of FIG. 1;

FIG. 10B is a side view of a shuttle of the insertion instrument of FIG.5 partially disposed within the expandable spinal implant of FIG. 1;

FIG. 10C is a side view of the shuttle of the insertion instrument ofFIG. 5, shown as being further advanced within the expandable spinalimplant of FIG. 1;

FIG. 10D is a side view of the shuttle of the insertion instrument ofFIG. 5, shown as being advanced even further within the expandablespinal implant of FIG. 1;

FIG. 11A is a rear, perspective view, of the insertion instrument ofFIG. 5, shown with the first tool of FIG. 8A;

FIG. 11B is a rear, perspective view, of the insertion instrument ofFIG. 5, shown with the first tool of FIG. 8A disposed within a fourththroughhole defined therein

FIG. 12 is a rear, perspective view, of another embodiment of anexpandable spinal implant provided in accordance with the presentdisclosure

FIG. 13 is an exploded view, with parts separated, of the expandablespinal implant of FIG. 12; and

FIG. 14 is a side view of the expandable spinal implant of FIG. 12.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present disclosure are now described in detail withreference to the drawings in which like reference numerals designateidentical or corresponding elements in each of the several views. Asused herein, the term “clinician” refers to a doctor, a nurse or anyother care provider and may include support personnel. Throughout thisdescription, the term “proximal” will refer to the portion of the deviceor component thereof that is closer to the clinician and the term“distal” will refer to the portion of the device or component thereofthat is farther from the clinician. Additionally, in the drawings and inthe description that follows, terms such as front, rear, upper, lower,top, bottom, and similar directional terms are used simply forconvenience of description and are not intended to limit the disclosure.In the following description, well-known functions or constructions arenot described in detail to avoid obscuring the present disclosure inunnecessary detail.

Referring now to the drawings, FIGS. 1-3 illustrate an expandable spinalimplant 10 provided in accordance with the present disclosure that iscapable being used with an insertion instrument 500 (FIG. 5), as will bedescribed in further detail hereinbelow. Expandable spinal implant 10includes an upper body 100, a lower body 200, leaf spring 250, and aratchet 300 including a shuttle nut 310, ratchet screw 400, and stopwasher 410 (FIG. 2). Upper and lower bodies 100, 200 cooperate to definea two part expandable spinal implant configured for positioning betweenadjacent vertebral bodies. Hinge pin 13 rotatably retains upper andlower bodies 100, 200 in order to permit upper and lower bodies 100,200, respectively, to rotate or articulate thereabout, therebyeffectuating lordosis of the spine. Ratchet 300, leaf spring 250,shuttle nut 310, ratchet screw 400, and stop washer 410 cooperate toprovide a locking mechanism to lock upper and lower bodies 100, 200 inan articulated position relative to each other, thereby maintaining thedesired lordosis of the spine. In this manner, rotation of ratchet screw400 causes shuttle nut 310 translate in a proximal or distal direction(i.e., towards or away from trailing end 108) thereby causing ratchet300 to translate between a locked and an unlocked position.

A first opening 100 a is defined through a top surface 110 of upper body100 and a second opening 200 a is defined through a bottom surface oflower body 200. First and second openings 100 a, 200 a define a cavitytherebetween and include a shape generally complimentary to the shape ofupper and lower bodies 100, 200, although it is contemplated that firstand second openings 100 a, 200 a may include any suitable shape, such assquare, oval, circular, or the like.

Ratchet 300 is slidably disposed on upper body 100 and includes aplurality of teeth 302 disposed thereon configured to engage acorresponding plurality of teeth 232 disposed on lower body 200 asratchet 300 is advanced from an unlocked position to a locked position.Once engaged, teeth 302 and 232 maintain lower body 200 and upper body100 in a selected position relative to each other. A through-bore 304 isdefined through ratchet 300 and is configured to slidably receiveratchet screw 400 therein. Stop washer 410 is fixedly secured to adistal end of ratchet screw 400, such that ratchet 300 may not beadvanced distally such that ratchet 300 becomes disengaged from ratchetscrew 400. Stop washer 410 may be retained on ratchet screw 400 by anymeans known in the art, such as bonding, welding, etc.

Ratchet screw 400 is rotatably disposed within upper body 100 andincludes a tool engaging recess 400 c defined therein configured toengage distal tip 606 a of first tool 600 (FIG. 8A). In this manner,rotation of first tool 600 effectuates rotation of ratchet screw 400,thereby effectuating movement of shuttle nut 310, as will be describedin further detail hereinbelow.

Leaf spring 250 includes a generally open trapezoidal profile and isconfigured and/or dimensioned to be interposed between a proximal facinginterior surface 100 b of first opening 100 a and shuttle 300. In thismanner, leaf spring 250 includes a backspan 252 and a pair of proximallyextending arms 254. Each arm 254 is oriented in a medial direction, suchthat arms 254 extend towards one another. A slot 254 a is defined on aproximal end of each arm 254 and is configured to engage a ridge 308defined on a distal end of ratchet 300.

Backspan 252 is configured to be disposed in recess 100 c defined inproximal facing interior surface 100 b of first opening 100 a, and eacharm of the pair of proximally extending arms 254 is compressed aninitial amount such that when leaf spring 250 is interposed betweenupper body 100 and ratchet 300, ratchet 300 is biased in a proximaldirection.

The open configuration of leaf spring 250 enables a clinician to packopenings 100 a, 200 a of upper and lower bodies 100, 200, respectively,with bone in-growth material, drugs, or other suitable materials orcompounds, as will be described in further detail hereinbelow. In thismanner, leaf spring 250 minimally impacts the volume of material thatcan be packed within openings 100 a, 200 a. However, it is contemplatedthat leaf spring 250 may include any suitable profile capable of biasingratchet 300 in a proximal direction, such as V-shaped, C-shaped,U-shaped, wave, etc. or leaf spring 250 may be any suitable biasingelement or elements, such as a coil spring, a plurality of coilssprings, Bellville washer(s) of any suitable profile, torsion, or thelike. Alternatively, it is contemplated that one or more coil springs,Bellville washers, or other suitable biasing elements may be disposedwithin cavity 306 of ratchet 300 (further detailed hereinbelow) suchthat the biasing element is interposed between shuttle nut 310 andratchet 300 thereby biasing ratchet 300 in a proximal direction. Inembodiments, the biasing element may be coaxially disposed aroundratchet screw 400.

A cavity 306 is defined through an upper surface 300 a of ratchet 300and is configured and dimensioned to receive shuttle nut 310 therein.Although shown as including a generally square profile, it iscontemplated that shuttle nut 310 may include any suitable profile, suchas circular, oval, rectangular, or the like. A threaded bore 310 c isdefined through a proximal face 310 a and a distal face (not shown) ofshuttle nut 310 and is configured to threadably engage ratchet screw400. In this manner, threaded bore 310 c is coaxially aligned withthrough-bore 304 of ratchet 300 when shuttle nut is fully nested withincavity 306. Shuttle nut 310 is configured to be translated proximallysuch that proximal face 310 a is drawn into contact with ratchet 300 andurges ratchet 300 towards a locked position (i.e., towards trailing end108). In this manner, leaf spring 250 biases ratchet 300 such that teeth302 and 232 engage one another. When placed in a locked position,shuttle nut 310 prevents ratchet 300 from translating in a distaldirection (i.e., towards leading end), thereby maintaining engagementbetween teeth 302 and 232.

Shuttle nut 310 is also configured to be translated distally such that adistal face (not shown) of shuttle nut 310 is drawn into contact withratchet 300 and causes ratchet 300 to translate to an unlocked position.In this manner, shuttle nut 310 causes ratchet 300 to overcome thebiasing force provided by leaf spring 250, thereby causing teeth 302 and232 to disengage, thereby allowing upper and lower bodies 100, 200 toarticulate relative to one another.

As can be appreciated, shuttle nut 310 is configured to be placed in anintermediate position where shuttle nut 310 does not urge ratchet 300 ina distal direction. Rather, shuttle nut 310 is placed in a positionwhere ratchet 300 is permitted to translate in a distal direction,thereby permitting teeth 302 and 232 to cam over one another. In thismanner, as teeth 302 and 232 cam over one another, upper and lowerbodies 100, 200 articulate relative to one another throughout aplurality of positions defined by positions in which teeth 302 and 232are engaged.

A plurality of threaded bores 140 a and 240 are defined through atrailing end 108 of upper body and a trailing end 208 of lower body 200,respectively, and are configured to threadably engage screws 540 ofinsertion instrument 500 (FIG. 7B). In this manner, expandable spinalimplant 10 may be releasably engaged to insertion instrument 500 topermit insertion, and manipulation thereof, within the intervertebralspace.

With reference to FIGS. 12-14, in an alternative embodiment, it iscontemplated that expandable spinal implant 10′ may not include a leafspring 250 or shuttle nut 310, and rather, ratchet 300′ is configured tothreadably engage ratchet screw 400′. Specifically, expandable spinalimplant 10′ includes an upper body 100′, a lower body 200′, and aratchet 300′ including a ratchet screw 400′ (FIG. 13). Upper and lowerbodies 100′, 200′ articulate relative to one another about hinge pin 13′similarly to that described above with respect to expandable spinalimplant 10. Ratchet 300′ and ratchet screw 400′ cooperate to provide alocking mechanism to lock upper and lower bodies 100′, 200′ in anarticulated position relative to each other, thereby maintaining thedesired lordosis of the spine. In this manner, ratchet screw 400′threadably engages ratchet 300′ such that rotation of ratchet screw 400′causes ratchet 300′ to translate between a locked and an unlockedposition. Expandable spinal implant 10′ is otherwise similar to that ofexpandable spinal implant 10, and therefore, additional description ofexpandable spinal implant 10′ is not detailed herein in the interest ofbrevity.

Upper and lower bodies 100, 200 are secured to a respective vertebralbody by means of bone screws 14 (FIGS. 4A-4C). In this manner, each bonescrew 14 substantially retains expandable spinal implant 10 in positionrelative to the adjacent vertebral bodies. As bone screws 14 are similarto one another, only one is described in detail herein. It is alsocontemplated that other suitable bone screws 14 be provided for use withexpandable spinal implant 10.

Bone screw 14 generally includes a shank 15 and a head 16. Shank 15defines a distal tip 15 a and pitched threading 15 b disposed aboutshank 15. Distal tip 15 a and pitched threading 15 b facilitate drivingbone screw 14 into bone and securement of bone screw 14 therein. Head 16of bone screw 14 defines a tool-engaging recess 16 a. Head 16 furtherincludes a thread 16 b for threadably engaging a lip 138 b, 238 bdefined in each one of the plurality of threaded bores 140 a, 240,respectively. Pitched threading 15 b has a pitch greater than that ofthread 16 b. Tool-engaging recess 16 a may have any shape and/ordimension suitable for transmitting rotational motion from a tool tobone screw 14 (e.g., square, hex, pozidrive, or the like).

For a detailed description of an exemplary expandable spinal implant andexemplary bone screws, reference can be made to U.S. patent applicationSer. No. 14/510,598, filed Oct. 9, 2014, and U.S. Patent ApplicationPublication No. 2014/0214166, filed Jan. 25, 2013, the entire contentsof each of which are hereby incorporated herein by reference.

Turning now to FIGS. 5-7B, an insertion instrument 500 provided inaccordance with the present disclosure is illustrated. Insertioninstrument 500 includes an elongate member 502 extending betweenproximal and distal ends defining longitudinal axis A-A. The proximalend of elongate member 502 includes a handle portion 504 having acircular cross-section. However, it is contemplated that handle portion504 may include any suitable cross-section capable of facilitatinggrasping, such as oval, square, rectangular, hexagonal, or the like.Handle portion 504 transitions to an intermediary shaft 506 disposeddistal of handle portion 504. Intermediary shaft 506 is co-axial withlongitudinal axis A-A and includes a generally cloverleaf shapedcross-section, although it is contemplated that intermediate shaft 506may be disposed eccentrically relative to longitudinal axis A-A. As canbe appreciated, intermediary shaft 506 may include any suitablecross-section, such as circular, oval, square, rectangular, hexagonal,or the like. In embodiments, intermediary shaft 506 is constructedmonolithically (i.e., constructed from a single piece of material);however, it is contemplated that intermediary shaft 506 may beconstructed from a plurality of elongate tubes that are fixedly securedtheretogether using any suitable means, such as welding, adhesive,fasteners, or the like. Although generally described as being formedmonolithically with elongate member 502, in certain embodiments,intermediary shaft 506 may be a separate component that is fixedlysecured to handle portion 504 using any suitable means, such as thosedescribed hereinabove.

Intermediary shaft 506 transitions to an end effector 508 extendingdistally therefrom, although it is contemplated that end effector 508may be separately formed from intermediary shaft 506 and fixedly securedthereto using any suitable means, such as those described hereinabove.Although illustrated as including a cross-section similar to that ofintermediary shaft 506, it is contemplated that end effector 508 mayinclude any suitable cross-section, such as circular, rectangular,square, oval, hexagonal, or the like. As best illustrated in FIG. 7B,end effector 508 includes a cavity 510 defined on an upper surface 508 bthereof configured to receive a shuttle 512 therein as will be describedin further detail hereinbelow. Cavity 510 includes a pair of opposedrails 510 a disposed on opposed side walls 510 b thereof. A worm gear514 (FIGS. 7A and 10A) is rotatably disposed within cavity 510 and isaxially aligned along longitudinal axis A-A. Worm gear 514 includes alength that is generally shorter than that of shuttle 512, although itis contemplated that worm gear 514 may include any suitable lengthcapable of advancing shuttle 512 (i.e., without shearing the teeth offof worm gear 514). A proximal end of the worm gear 514 includes a toolengaging recess 514 a defined therein such that a suitable tool can beinserted therein and effectuate rotational motion thereon. Tool engagingrecess 514 a may be any suitable shape capable of transmitting therotational motion of the tool to worm gear 514, such as hexalobe, torx,square, pozidrive, or the like. Worm gear 514 may be rotatably retainedwithin cavity 510 using any suitable means known in the art, such aspillow blocks, plates, snap-fit, spindle, or the like. In onenon-limiting embodiment, worm gear 514 is retained within cavity 510 bymeans of a pair of feet (not shown) extending from proximal and distalends of worm gear 514 retained within corresponding grooves (not shown)defined within cavity 510. Although a distal end surface 508 a of endeffector 508 is generally shown as including an arcuate profile, it iscontemplated that distal end surface 508 a may include any suitableshape that corresponds to the shape of the trailing ends 108, 208 ofexpandable spinal implant 10 such that distal end surface 508 a of endeffector 508 may sit flush against trailing ends 108, 208 of expandablespinal implant 10.

As best illustrated in FIGS. 7A and 7B, shuttle 512 includes asubstantially wedge shaped distal end 512 a decreasing in thickness in adistal direction along longitudinal axis A-A, although other suitableprofiles are also contemplated, such as concave, convex, or the like.Shuttle 512 includes a pair of opposed slots 516 defined in opposed sidesurfaces 518 thereof. Each one of the pair of opposed slots 516 isconfigured to slidably receive a respective one of the pair of rails 510a of cavity 510. In this manner, shuttle 512 is slidably retained withincavity 510 such that shuttle 512 is only permitted to advance or retreatalong longitudinal axis A-A (i.e., 2 degrees of freedom), and isprohibited from traveling in any other direction (i.e., pitch, yaw, orroll). A lumen 522 is defined through a proximal end surface 524 ofshuttle 512 and extends through a distal end surface 526 thereof. Lumen522 is configured to receive a suitable tool capable of engaging ratchetscrew 400, as will be described in detail hereinbelow. A distal end ofshuttle 512 includes a relief 528 defined therein extending proximallyalong longitudinal axis A-A. Relief 528 removes a lower portion of thewedge shaped distal end 512 a and extends proximally therefrom (FIG.7B). Relief 528 terminates before the midpoint of shuttle 512, such thatwhen shuttle 512 is advanced toward expandable spinal implant 10, thelower portion of the wedge shaped distal end 512 a of shuttle 512 doesnot impact lower body 200 of expandable spinal implant 10. Inembodiments, shuttle 512 may not include a relief 528. A plurality oftransverse grooves (not shown) are defined in a lower surface (notshown) of shuttle 512 and are configured to threadably engage worm gear514 such that when worm gear 514 is rotated, shuttle 512 is advanced orretreated within cavity 510 along longitudinal axis A-A.

Additionally, insertion instrument 500 includes a plurality ofthroughholes defined therethrough (FIGS. 5 and 6). A first throughhole530 is defined through proximal end surface 502 a of elongate member 502and extends through a proximal end surface 510 b of cavity 510. Firstthroughhole 530 is co-axially aligned with worm gear 514 (i.e., alonglongitudinal axis A-A). First throughhole 530 includes a suitablediameter capable of receiving a suitable tool such that the tool mayengage tool engaging recess 514 a of worm gear 514, as will be describedin further detail hereinbelow. A second and third throughhole 532 and534 are defined through proximal end surface 502 a of elongate member502 and extend through a distal end surface 508 a of end effector 508(FIG. 7B). Second and third throughholes 532, 534 are arranged spatiallyabout first throughhole 530 such that when insertion instrument 500 isaligned with expandable spinal implant 10, each of second and thirdthroughholes 532, 534 are co-axially aligned with each of the pair ofthreaded bores 140 a of upper body 100. Fourth throughhole 536 isdefined through proximal end surface 502 a of elongate member 502 andextends through proximal end surface 510 c of cavity 510. Fourththroughhole 536 is disposed above first throughhole 530 and isco-axially aligned with lumen 522 of shuttle 512 and ratchet screw 400of expandable spinal implant 10 such that a suitable tool may beadvanced therethrough and engage tool receiving recess 400 c of ratchetscrew 400 to lock or unlock expandable spinal implant 10, as will bedescribed in further detail hereinbelow.

A pair of screws 540 is disposed in a distal portion of each one ofsecond and third throughholes 532, 534, respectively, and includes athreaded distal portion 542 and a head 544 defined on a proximal portionthereof. Each screw of the pair of screws 540 includes a length suchthat only a small portion of each screw 540 is disposed within each ofsecond and third throughholes 532, 534 (i.e., mainly the head 544 and ashort portion of a shank of the screw 540). In this manner, each screwof the pair of screws 540 only includes a length that is suitable toensure that insertion instrument 500 remains securely fastened to spinalimplant 10. A tool engaging recess 544 a is defined within head 544 andis configured to engage a suitable tool as will be described in furtherdetail hereinbelow. Although generally shown as including a hexalobeconfiguration, tool engaging recess 544 a may include any suitableconfiguration capable of transmitting torque from the tool to screw 540,such as square, pozi, hex, or the like. The screws 540 are configured tobe advanced within second and third throughholes 532, 534 such that adistal end (not shown) of head 544 may abut a corresponding boss (notshown) defined on a distal end of second and third throughholes 532,534. Threaded distal portion 542 is configured to extend distallythrough second and third throughholes 532, 534 and threadably engagethreaded bores 140 a of upper body 100.

With reference to FIG. 8A, a first tool suitable for securing insertioninstrument 500 to expandable spinal implant 10 is illustrated andgenerally identified by reference numeral 600. First tool 600 includesan elongate body 602 extending between proximal and distal ends 604 and606, respectively. Although illustrated as including a circularcross-section, it is contemplated that first tool 600 may include anycross-section suitable for grasping, such as square, hexagonal, or thelike. A circumferential groove 608 is defined within an outer surface602 a of elongate body 602 adjacent to proximal end 604 and isconfigured to enable a suitable handle or driver (not shown) to retainfirst tool 600 thereon via snap fit or other suitable mechanical meanscapable of selectively engaging circumferential groove 608. A relief(not shown) or other suitable feature may be defined within outersurface 602 a of elongate body to enable rotational motion of the handleto be transferred to first tool 600. Elongate body 602 transitions to atapered end surface 602 b on a distal end 606 thereof which terminatesin a distal tip 606 a. Distal tip 606 a is configured to engage toolengaging recess 544 a of each of the pair of screws 540 and toolengaging recess 400 c of ratchet screw 400, and therefore, match theconfiguration of tool engaging recesses 544 a, 400 c such that rotationof first tool 600 is transferred to the pair of screws 540 and/orratchet screw 400. In embodiments, distal tip 606 a includes a hexalobeconfiguration.

A second tool suitable for manipulating shuttle 512 along longitudinalaxis A-A is illustrated in FIG. 9A and is generally identified byreference numeral 700. Second tool 700 includes an elongate body 702extending between proximal and distal ends 702 a and 702 b,respectively, and includes a generally circular cross section; althoughother cross-sections suitable for grasping are contemplated, such assquare, hexagonal, or the like. A circumferential groove 704 is definedwithin an outer surface 702 c of elongate body 702 adjacent proximal end702 a and is configured to enable a suitable handle or driver (notshown) to retain first tool 700 thereon via snap fit or other suitablemechanical means capable of selectively engaging circumferential groove704. A bulge or protuberance 706 is disposed on outer surface 702 c ofelongate member 702 distal of circumferential groove 704. Bulge 706includes a flat annular proximal surface 706 a disposed on a proximalend thereof that extends between outer surface 702 c of elongate member702 and an outer surface 706 b of bulge 706. A pair of reliefs 706 c isdefined within flat annular surface 706 a and extends distallytherefrom. The pair of reliefs 706 c extends from outer surface 702 c ofelongate member 702 to outer surface 706 b of bulge 706 and areconfigured to permit torque to be transferred from a suitable handle ordriver to second tool 700. An annular groove 706 d is defined withinouter surface 706 b of bulge 706 distal of the pair of reliefs 706 c.Distal of annular groove 706 d, outer surface 706 b tapers towards outersurface 702 c of elongate body 702. Distal end 702 b of elongate body702 defines a distal tip 702 d configured to engage tool engaging recess514 a of worm gear 514, and therefore, match the configuration of toolengaging recess 514 a of worm gear 514 such that rotation of second tool700 is transferred to worm gear 514, thereby effectuating movement ofshuttle 512 along longitudinal axis A-A. In embodiments, distal tip 702d includes a hexalobe configuration.

With reference to FIGS. 5-11B, the insertion of an expandable spinalimplant 10 using insertion instrument 500 is illustrated. Initially,shuttle nut 310 is placed in a first, open position by rotating ratchetscrew 400 in a first direction using a suitable tool inserted withintool engaging recess 400 c of ratchet screw 400. Alternatively, ratchet300 may be placed in an intermediate position where leaf spring 250biases ratchet 300 in a proximal direction such that teeth 302, 232 arein engagement, but are not locked theretogether (i.e., teeth 302, 232may cam over one another allowing expansion, but preventing collapse).Next, expandable spinal implant 10 is affixed to insertion instrument500 by threadably engaging the pair of screws 540 with the correspondingplurality of threaded bores 140 a of upper body 100. In this manner,each one of the pair of screws 540 is advanced within second and thirdthroughbores 532, 534 of insertion instrument 500. Next, insertioninstrument 500 is aligned with expandable spinal implant 10 such thateach of the pair of screws 540 is aligned with a corresponding threadedbore of the plurality of threaded bores 140 a of upper body 100 (FIGS.7A and 7B). At this point, first tool 600 is advanced within secondthroughhole 532 until distal tip 606 a engages tool engaging recess 544a of the screw 540, at which time first tool 600 may be rotated tothread the distal threaded portion 542 of the first screw of the pair ofscrews 540 within the first threaded bore of the plurality of threadedbores 140 a of lower body 100 (FIGS. 8A and 8B). The process is repeatedfor the second screw of the pair of screws 540.

Next, if shuttle nut 310 of expandable spinal implant 10 was notinitially placed in an intermediate position first tool 600 is advancedwithin fourth throughhole 536 until distal tip 606 a engages toolengaging recess 400 c of ratchet screw 400, and thereafter rotated suchthat first tool 600, and thereby ratchet screw 400, are rotated a firstdirection to place shuttle nut 310 in an intermediate position (FIGS.11A and 11B). The intervertebral space is then prepared, e.g., damagedor diseased tissue is removed. Thereafter, the cavity defined betweenopenings 100 a, 200 a of upper and lower bodies 100, 200, respectively,may be packed with bone in-growth material, drugs, or other suitablematerials or compounds. Examples of such materials are allograftmaterial, autograft material, calcium phosphate/bone marrow aspirate(BMA), autogenous bone material, or synthetic materials comprised of abiocompatible, osteoconductive, osteoinductive, or osteogeneic materialsuch as VITOSS® Synthetic Cancellous Bone Void Filler material. At thispoint, expandable spinal implant 10 is advanced within an incisionwithin the patient and thereafter, a previously prepared intervertebralspace of the patient's spine. It is contemplated that expandable spinalimplant 10 may be advanced within the previously prepared intervertebralspace until upper and lower bodies 100, 200 abut a respective vertebralendplate of the patient's spine. Bone screws 14 (FIGS. 4A-4C) are theninserted within screw holes 238 of lower body 200 and are driven intoone of the adjacent vertebral bodies. Next, second tool 700 is advancedwithin first throughhole 530 until distal tip 702 d engages toolengaging recess 514 a of worm gear 514 (FIGS. 9A and 9B). Thereafter,second tool 700 may be rotated a first direction to cause expandablespinal implant 10 to articulate about hinge pin 13 to a desiredorientation. In this manner, rotation of second tool 700 causes shuttle512 to be advanced in a distal direction toward expandable spinalimplant 10. As second tool 700 is rotated further, shuttle 512 isfurther advanced distally such that wedge shaped distal end 512 a ofshuttle 512 contacts lower body 200, thereby causing lower body 200 toarticulate about hinge pin 13 relative to upper body 100 as the wedgeshaped distal end 512 a increases in thickness (FIGS. 10A-10D). Thisarticulation causes teeth 302 and 232 to cam over one another, therebypermitting upper and lower bodies to articulate about hinge pin 13 andincrease in height, but not collapse (i.e., expandable spinal implant 10is partially locked). Articulation of upper body 100 and lower body 200relative to each other effectuates lordosis of the spine. Alternatively,it is contemplated that upper body 100 and lower body 200 may bearticulated relative to each other to effectively fill theintervertebral space without effectuating lordosis of the spine. Thedesired location of upper body 100 and lower body 200 is selected basedon the desired lordosis of the spine. In one exemplary embodiment, teeth302 and 232, and thereby shuttle 512, are configured to permit theselection of three positions. Once a desired location has been selected,ratchet screw 400 is rotated in the second, opposite direction, usingfirst tool 600, to lock the position of upper body 100 relative to lowerbody 200 by drawing shuttle nut 310 a proximal direction, therebydrawing teeth 302 of ratchet 300 into engagement with teeth 232 of lowerbody 200 (FIGS. 11A and 11B). Thereafter, insertion instrument 500 isdisengaged from expandable spinal implant 10 using first tool 600 andthereafter, removed from the incision. Once insertion instrument 500 isdisengaged from expandable spinal implant 10, a final bone screw 14 isinserted into remaining screw hole 138 of upper body 100 and is driveninto the other adjacent vertebral body. Alternatively, each bone screw14 may be inserted into screw holes 138, 238 of upper and lower bodies100, 200, respectively after insertion instrument 500 is disengaged fromexpandable spinal implant 10. Further, it is contemplated that pilotholes be drilled within each respective vertebral body before drivingthe bone screws 14 therein in order to aid in the driving of bone screws14 therein.

In some embodiments, the position of upper body 100 relative to lowerbody 200 may be set prior to inserting expandable spinal implant 10within the intervertebral space. Once the position of upper body 100relative to lower body 200 is set, the expandable spinal implant 10 maybe advanced into the previously prepared intervertebral space untilupper and lower bodies 100, 200 abut a respective vertebral endplate ofthe patient's spine. Thereafter, the position may continue to bemanipulated until the desired lordosis is achieved using the procedurepreviously described above.

In an alternative embodiment, where ratchet 300′ threadably engagesratchet screw 400′, ratchet 300′ is placed in a first, open position byrotating ratchet screw 400′ in a first direction using a suitable toolinserted within tool engaging recess 400 c′ of ratchet screw 400′.Alternatively, ratchet 300′ may be placed in a first, open position,after affixing insertion instrument 500 to expandable spinal implant10′. Thereafter, the procedure detailed above may be followed. Once thedesired lordosis is achieved, ratchet screw 400′ may be rotated in thesecond direction using tool 600 to lock upper body 100′ and lower body200′ in the selected position.

The processes detailed above may be repeated as many times as theprocedure requires, whether it be for the same expandable spinal implant10 or for a plurality of expandable spinal implants 10 as required bythe procedure being performed.

It will be understood that various modifications may be made to theembodiments of the presently disclosed expandable spinal implant.Therefore, the above description should not be construed as limiting,but merely as exemplifications of embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of thepresent disclosure.

What is claimed is:
 1. An insertion instrument for expandable spinalimplants, comprising: an elongate member including a handle portion on aproximal end thereof and an end effector on a distal end thereof, theend effector configured to be releasably engaged to an expandable spinalimplant; a shuttle slidably disposed within a cavity defined in the endeffector, the shuttle including a wedged shaped distal end configured toengage the expandable spinal implant and a plurality of transversegrooves defined in a lower surface of the shuttle; and a worm gearrotatably disposed within the cavity defined in the end effector andexternal to the expandable spinal implant, the worm gear having a lengththat is shorter than a length of the shuttle, the worm gear inmechanical communication with the shuttle by threadable engagement ofthe worm gear with the transverse grooves such that rotation of the wormgear effectuates sliding movement of the shuttle, wherein distal slidingmovement of the shuttle effectuates articulation of the expandablespinal implant.
 2. The insertion instrument of claim 1, furtherincluding a first tool capable of coupling the end effector to theexpandable spinal implant.
 3. The insertion instrument of claim 2,further including a second tool capable of engaging the worm gear andeffectuating the rotation thereof.
 4. The insertion instrument of claim3, wherein the elongate member further includes a plurality ofthroughholes defined therethrough.
 5. The insertion instrument of claim4, wherein the plurality of throughholes includes a first throughholeconfigured to receive the second tool therethrough.
 6. The insertioninstrument of claim 5, wherein the plurality of throughholes includes asecond and a third throughhole, the second and third throughholesconfigured to receive the first tool therethrough, thereby enabling theend effector to be releasably engaged to the expandable spinal implant.7. The insertion instrument of claim 6, wherein the plurality ofthroughholes includes a fourth throughhole configured to receive thefirst tool therethrough to lock a position of a lower body in relationto a position of an upper body of the expandable spinal implant.
 8. Theinsertion instrument of claim 6, further including a plurality ofscrews, wherein each of the second and third throughholes is configuredto receive a respective screw of the plurality of screws therein, theplurality of screws being configured to releasably couple the endeffector to the expandable spinal implant.
 9. The insertion instrumentof claim 1, wherein the cavity defined in the end effector includes apair of opposed rails disposed on side surfaces thereof, the pair ofopposed rails configured to slidably engage a corresponding pair ofopposed slots defined within side surfaces of the shuttle.